﻿// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information
// 
// Licensed to the Apache Software Foundation (ASF) under one or more
// contributor license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright ownership.
// The ASF licenses this file to you under the Apache License, Version 2.0
// (the "License"); you may not use this file except in compliance with
// the License. You may obtain a copy of the License at
// 
// http://www.apache.org/licenses/LICENSE-2.0
// 
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// 

using System;
using System.IO;

namespace log4net.Util.PatternStringConverters
{
    /// <summary>Write the current threads username to the output</summary>
    /// <remarks>
    /// <para>
    /// Write the current threads username to the output writer
    /// </para>
    /// </remarks>
    /// <author>Nicko Cadell</author>
    internal sealed class UserNamePatternConverter : PatternConverter 
    {
        /// <summary>Write the current threads username to the output</summary>
        /// <param name="writer">the writer to write to</param>
        /// <param name="state">null, state is not set</param>
        /// <remarks>
        /// <para>
        /// Write the current threads username to the output <paramref name="writer"/>.
        /// </para>
        /// </remarks>
        protected override void Convert(TextWriter writer, object state) 
        {
#if (NETCF || SSCLI || NETSTANDARD1_3)
            // On compact framework there's no notion of current Windows user
            writer.Write( SystemInfo.NotAvailableText );
#else
            try
            {
                System.Security.Principal.WindowsIdentity windowsIdentity = null;
                windowsIdentity = System.Security.Principal.WindowsIdentity.GetCurrent();
                if (windowsIdentity != null && windowsIdentity.Name != null)
                {
                    writer.Write(windowsIdentity.Name);
                }
            }
            catch(System.Security.SecurityException)
            {
                // This security exception will occur if the caller does not have 
                // some undefined set of SecurityPermission flags.
                LogLog.Debug(declaringType, "Security exception while trying to get current windows identity. Error Ignored.");

                writer.Write(SystemInfo.NotAvailableText);
            }
#endif
        }

        /// <summary>The fully qualified type of the UserNamePatternConverter class.</summary>
        /// <remarks>
        /// Used by the internal logger to record the Type of the
        /// log message.
        /// </remarks>
        private static readonly Type declaringType = typeof(UserNamePatternConverter);
    }
}
